Sasa.Atomics - Simpler, More Scalable Atomic Operations

This is the nineteenth post in my ongoing series covering the abstractions in Sasa. Previous posts:

• Sasa.Parsing - type-safe, extensible lexing and parsing framework
• Sasa.Dynamics - type-safe polytypic/reflective programming
• Sasa.Func - Type-Safe Delegate Combinators
• Sasa.Option - Handling Optional Values
• Sasa.Result - Handling Exceptional Values
• Sasa.Numbers - Generic Number Extensions
• Sasa.Strings - General String Extensions
• Sasa.Types - Runtime Types And CLR Metadata
• Sasa.Weak - Typed Weak References
• Sasa's Tuples
• Sasa's Core Interfaces
• Sasa.Events - Type-Safe, Null-Safe, Thread-Safe Events
• Sasa.Web.Url64 - URL-Safe Base64 Encoding
• Sasa.Operators<T> - Generic Arithmetic and Logical Operators
• Sasa.IO.FilePath - Easy and Safe Path Manipulations
• Sasa.IO.Streams - Convenient Stream Extensions
• Sasa.Linq.Enumerables - Extensions on IEnumerable<T>
• Sasa.Either - Simple Sums for .NET

The System.Threading namespace contains a number of useful abstractions for concurrent programming. The Interlocked static class in particular ought to be in every programmer's toolbox. However, the CompareExchange API doesn't always lend itself to the cleanest algorithms. Furthermore, under medium to high contention, even atomic compare-and-swap operations don't scale well.

Enter Sasa.Atomics, which provides a simpler API for atomic operations and implements the lightweight contention management scheme from the paper described above. Constant backoff contention management requires no state, and incurs virtually no overhead in low contention scenarios, and it scales quite well under medium to high contention.

Sasa.Atomics.Set

Sasa.Atomics.Set is a set of extension methods which perform a compare-and-exchange operation, and return true if the operation succeeds:

string o = "hello";
...
if (Atomics.Set(ref o, o + " world!", o))
    Console.WriteLine(o);
// output:
// hello world!

Sasa.Atomics.SetFailed

Sasa.Atomics.Set is a set of extension methods which perform a compare-and-exchange operation, and return true if the operation fails:

string o = "hello";
...
while (Atomics.SetFailed(ref o, o + " world!", o)) { }
// output:
// hello world!